code: def selection_change(attrname, old, new):
      t1, t2 = ticker1.value, ticker2.value
      data = get_data(t1, t2)
  
      if selected := source.selected.indices:
          data = data.iloc[selected, :]
  
      update_stats(data, t1, t2)
  
file_path: bokeh/examples/server/app/stocks/main.py
imports: from functools import lru_cache
  from bokeh.layouts import column, row
  from bokeh.models import ColumnDataSource, PreText, Select
  from bokeh.plotting import curdoc, figure
label_desc: Use image node_id 7 for calling a global function with example usage: selection_change(attrname, old, new) without return types